DE1109546B - Activation system for vehicle brakes, in particular vehicle brakes - Google Patents

Description

The invention relates to an actuation system for vehicle brakes, in particular vehicle brakes, with a hydraulic primary circuit, which has a master cylinder to be actuated by means of the brake pedal and includes wheel brake cylinders in line with the master cylinder, and with a secondary circuit with movable secondary organs in each brake that support the supporting forces Record brake shoes, as well as clutch means, which the supporting forces in the secondary organs align the different brakes.

In the known systems of the type just described, there are all hydraulic primary linkages always under the same pressure, even if a counteraction develops on the secondary side. The brake, where the strongest frictional force occurs between the drum and the jaws, plays plays a special role here and causes oil to shift in the secondary circuit. This brake generates therefore, by the rotation of their brake shoes, reverse rotations of the brake shoes of the others Brakes. These oil shifts do not stop until the moment the others Return the brakes to their original position as far as the stop. This leads to sudden and unpredictable Reversals of the flow in the hydraulic circuits, and especially in so-called Servo brakes cause malfunctions.

The invention is based on the object of eliminating the disadvantages of the known actuating systems and accordingly to create a facility with excellent alignment.

The object is achieved in that in an actuation system for vehicle brakes with the Features of the first paragraph according to the invention for the two brakes of the two wheels at least each axis has a primary hydraulic linkage with a pressure chamber and an intermediate piston in the Master cylinder is provided that means are provided which cause the intermediate piston when Brakes cover the same distance, and other means by which a hydraulic connection between the primary hydraulic linkage can be established or separated.

The actuation system according to the invention ensures that the same amounts of fluid are displaced within the primary hydraulic linkage, while the counteraction of the secondary system builds up. The oil column in each primary hydraulic linkage between the master cylinder and the primary piston in the brake cylinder prevents the vehicle brake actuation system from returning when driving forward,
in particular motor vehicle brakes

Applicant:

Societe Anonyme Frangaise du FERODO, Paris

Representative: ~ DipL = Ing_AJBohf, Dr.-Ing. H. Fincke,

Dipl.-Ing. H. Bohr and Dipl.-Ing. S. Staeger,

Patent Attorneys, Munich 5, Müllerstr. 31

Claimed priority:
France 8 March 1956

Pierre Andre Lepelletier, Chatou, Seine-et-Oise

(France),
has been named as the inventor

Brake shoes to the stop under the influence of the pressure in the secondary circuit, unless somewhere a line break should have occurred. With the system according to the invention, therefore, a faultless one is obtained Continuity of the brake shoe movement when initiating the braking process and a soft one as well as uniform transmission from brake to brake.

Further features of the invention are characterized in the patent claims, and further advantages of the invention emerge from the following description of exemplary embodiments in conjunction with the drawings. It shows

1 shows a longitudinal section through the master cylinder of an actuation system according to the invention,

Fig. 2 is a schematic representation of the hydraulic circuits,

3 is a view of a brake,
4 shows, on an enlarged scale, a partial section of a modification of the embodiment according to FIG. 1, FIG. 5 shows a schematic representation similar to FIG. 2, but with a different arrangement of the hydraulic circuits,

6 shows a further embodiment of the hydraulic circuits,

7 shows a longitudinal section through a particular arrangement for the arrangements shown in FIG. 5 or 6 master cylinder suitable for hydraulic circuits,

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Fig. 8 shows a modified detail of the master cylinder shown in Fig. 7;

9 shows a longitudinal section through a brake cylinder with means for filling the secondary circuit,

10 and 11 sections of the same cylinder, but in different operating positions,

12 shows a plan view of a disc brake with a hydraulic secondary circuit,

13 shows a longitudinal section through a hydraulic device assigned to this brake,

Fig. 14 is a plan view of two brakes of the type shown in Fig. 12, but which are supported by a mechanical secondary connection are coupled.

In the embodiment shown in FIGS. 1 to 3, the master cylinder controlling the brake system is in the master cylinder 10, a sliding piston 11 is arranged, the movements of which are controlled by the brake pedal 12. In the cylinder 10, a further piston 13 is also arranged displaceably. The shafts 14 and 15 of the Pistons 11 and 13 are hollow and facing each other, the second extending into the first around the To improve the centering of the arrangement. The space 16 of the cylinder 10 between the pistons 11 and 13 is filled with oil and provided with various connecting channels 17 to ensure that both inside and outside the piston shafts 14 and 15, the same pressure prevails.

The space 16 is at 18 with an oil tank 19 via a check valve 20 of a type known per se in connection, the shaft 21 of which cooperates with the piston 11. When the piston 11 is in its In the rest position, he holds the shaft 21 in an inclined position, in which the oil in both directions can flow through the valve 20. When the piston 11 is pushed into the cylinder, there he releases the shaft 21, the valve 20 allowing the oil to flow in the direction of the container 19 - space 16, but prevented in the opposite direction.

The room 16 is also at 22 with a line

23 in connection via a check valve 24, the shaft 25 of which interacts with the piston 13. When the piston 13 is in its rest position, it holds the shaft 25 in an inclined position in which the oil in both directions through the valve

24 can pass through. When the piston 13, seen in Fig. 1, is pushed to the left, it gives the Shaft 25 free, so that the valve 24 then only allows the oil to flow in the direction of space 16 —line 23 allows.

A spring 26 acts between the piston 11 and an abutment 27 in the shaft 15 of the piston 13, while a spring 28 acts between the abutment 27 and a small piston 29 which is displaceable is arranged in the piston 13. The two springs 26 and 28 can in certain cases by a single Spring to be replaced.

The small piston 29, which, as shown, with regard to the installation in the base 27 a of the Shaft 15 can be in several parts, has an end 30 which is in a connecting chamber provided in piston 13 31 works. This end 30 is provided with seals 32, which are used to Orifices 33 of four channels 34 provided in the piston 13 and leading into the chamber 31 are closed off. These channels 34 are connected to tubular extension pieces 35 attached to the piston 13. A piston 36 is slidably disposed around each extension 35 and is in the interior of a bore

37 is performed. The four bores 37, which correspond to the four extension pieces 35, are in the part 38 which is screwed into the end of the cylinder 10 at 39.

In the vicinity of the piston 13, each tubular extension piece 35 has one or more openings 40, through which its interior is in communication with a ίο chamber 41 that contains the attachment pieces 35 surrounds and in the cylinder 10 as well as in the part

38 is limited by the piston 13 and the piston 36. The chamber 41 stands at 42 with a container 43 in connection. A seal 44 is arranged on each extension piece 44 in the vicinity of the openings 40, which cooperates with the end 45 of the rod of the piston 36 to close the openings 40. The piston 36 is on the extension piece 35 between a stop position at 47, in which the Openings 40 are released, and a stop position at 44, in which the openings 40 are covered, arranged displaceably. In the sense of returning the piston 36 to the last-mentioned position a spring 46 acts, which is supported between the piston 36 and the bottom of the bore 37. In the However, a rest position shown in Fig. 1 holds a stop 47 a projecting into the bores 37 Piston 36 against the action of springs 46 in such a position that the openings 40 are exposed.

Four lines 48 are connected to the four bores 37. Residual pressure valves 49 known per se Art are provided at the connection point of the lines 48 and at that of the line 23 in such a way that that they allow the oil flow in both directions, the flow in the direction of the pipe is free, but happens in the opposite direction against the action of a weak spring.

The four lines 48 emanating from the master cylinder 10 (FIG. 2) form elements of the primary circuit the brake system and are connected to the primary circuits 50 (FIG. 3) of the brake cylinders 52. the Line 23 forms part of the secondary circuit of the brake system and is connected to secondary chambers 51 the cylinder 52 in communication. The arrangement of the brakes and the brake cylinder is such that the Equalization of the braking effect when driving forward in the direction of arrow F predominantly through the secondary circuit is determined in relation to the primary circuit.

3 shows an exemplary embodiment of a braking device, in which the brake shield 53 and 54 a brake drum which rotates in the direction of the arrow F when traveling forwards are denoted. In the direction of rotation of the drum 54, two brake shoes 55 and 56 are arranged one behind the other, which are connected to one another by a connecting rod 57. The jaw 55 is actuated by a piston 58 which is movable in the primary chamber 50 of the cylinder 52.

The other jaw 56 is intended for cooperation with a piston 59 in the secondary chamber 51 of the cylinder 52 is movable. At 60, a central wall in the cylinder 52 is referred to, which the bottom 61 of the primary chamber 50 and the bottom 62 of the secondary chamber 51 forms. A U-shaped Return spring 63 connects the two jaws 55 and 56, while for the return of the two jaws in a certain rest position, in which in the

Secondary chamber 51 a larger oil supply remains, a centering device is provided. This centering device has a rod 64 which penetrates the body of the cylinder 52 and between two approaches 58 a and 59 a of the piston 58 and 59 is arranged so that they have a lower limit of the Forms distance between the two pistons from each other. The rod 64 is provided with a collar 65 which is attached to a nut 66 is applied, which is adjustable in the

Arrow F. Oil is transferred from the primary chambers 50 to the master cylinder via the independent lines 48 10 while the secondary circuit 23 is used to supply oil to the secondary chambers 51 he follows.

The piston 13 is returned to the right (in the drawing) until the primary pistons 58 come to rest on the base 61 of the chambers 50. The piston 13 comes to a standstill in a position in which the body of the cylinder 52 is screwed in. Between io in which he holds the shaft 25 inclined, so that the Vendem collar 65 and a support surface 68 of the cylinder 24 is kept half open. With further Niederders 52 a return spring 67 is arranged, while a spring 69 the piston 59 in contact with the
Holds jaws 56 in the rest position.

If the pedal 12 is pressed while braking, 15
the piston 11 begins to release the stem 21 of the feed valve 20. With valve closed 20
11 oil is passed through by a movement of the piston
conveyed the line 23, the piston 13 being displaced at the same time. Through this, the direction of travel is first turned out, the oil content of its secondary, the openings 40 being closed by reducing the sealing chambers 51 and reducing the chamber 51 of the ge

When the pedal 12 is pressed, the oil in the space 16 via the circuit 23 into the chambers 51 of the brake cylinder repressed.

If for any reason one of the lines 48 breaks, the corresponding brake is only by means of of the secondary circuit 23 brought into effect. When driving forward, the brake shoes of the other guide Braking a small complementary turning movement in

lines 44 come to rest at the ends 45, whereby the four primary lines 48 from space 41 be separated and independent, since the orifices 33 at 32 by the piston 29 under the action the spring 28 are closed. The intermediate pistons 36 then press oil into the four lines 48, the piston 13 partially releasing the stem 25 of the valve 24. The pressure in the management

disturbed brake is filled and the stroke of the pedal 12 increases slightly. When reversing is no change found.

If a break occurs in the secondary circuit 23, none of the chambers 51 is supplied. The piston 11 comes to rest on the shaft 15, while the pistons 36 press oil into the lines 48 until the jaws 55 and 56 in contact with drum 54

gen 48 and in space 16 at the same time, with the 30 coming, with the pistons 59 against the base 62 Arrangement is made so that the pressure in the room are pressed. If the Pe-16 is stepped down further, which acts in the same sense as the spring 28 that

Openings 33 holds tightly closed.

An application movement is applied to the four brakes simultaneously through the primary chambers 50 and the secondary chambers 51 communicated, the primary pistons 58 movements that are identical or proportional to one another run, whereby a positive hydraulic clutch between the piston 13 and

dals 12, since the pressure effect generated in the lines 48 the existing in the space 16 and exceeds the pressure action supported by the spring 28, the piston 29, as seen in FIG. 1, to the right pushed back and the mouths 33 of the channels 34 are released, so that the lines 48 with each other are in communication via the chamber 31. In this way you get the usual hydrau each the piston 58 and an effective filling of the 40 lischen pressure equalization. When driving forward, the Primary chambers 50 is guaranteed. Braking force the same as before the breakage of the se-

When traveling forwards, the jaws 55 and 56, as soon as they come into contact with the drums 54, a back pressure on the secondary side. The jaws 55 and 56 rotate around the Wheel axis in the sense of the direction of travel. The secondary chambers 51 become oil via the secondary circuit 23 returned to the master cylinder 10, while an equal flow of oil to the primary chambers 50 takes place via the now independent lines 48.

The piston 13 accompanies this movement, whereby he
completely releases the stem 25 of the valve 24, which is below
the pressure in circuit 23 is firmly closed, the
compared to that in room 16 a very high value
occupies. At the same time, the oil volume in space 55 is a permanent connection with the filling tank 16 is set at a constant value, whereby 19 under static pressure and on the other hand a rigid coupling of the two pistons 11 and 13 stroke of the pedal 12 is ensured under the action of the space in each case . 16 generated pressure can be compensated.

When the pedal 12 is further depressed, the arrangement according to FIG.

Represents braking effect with predominant equalization by 60 changed part of the pump shown in Fig. 1, reinforces the secondary circuit. When the pedal 12 is released, the transition pressure that isolates the test is given the moving parts return to their secondary lines 48 instead of at a value of Rest position back. approximately zero set to a higher value.

When driving backwards the jaws 55 and In Fig. 4 the piston 13 can be seen again, in wel-56, once in contact with the brake drums 65 chem the connection chamber 31 is provided, the 54 come, a counter pressure on the primary side. Shank 15 of this piston with its base 27a and The jaws 55 and 56 rotate the small piston 29. However, in this case there is one around the wheel axis opposite to the direction of the spring instead of between the piston 29 and the counter-

Kundärkreises 23, while it is less when reversing due to the fact that both jaws act as draining jaws.

It should also be mentioned that during normal operation, the secondary circuit with a replenishment source 16 to 19 is in connection and this connection in the idle state and at the beginning of each actuation of the Brake pedal 12 is effective, while it is interrupted when the pedal is further depressed at 24 will. The pressure in the replenishment source 16 depends on the force on the pedal 12, so that the changes in the capacity or liquid losses of the secondary circuit 23 on the one hand in the idle state

bearing 27 arranged between the piston 29 and the Grand 27 a. It works in the opposite sense as the spring 28 in FIG. 1 and tends to connect the lines 48 via the chamber 31 to make it effective.

In the idle state, the chamber 31 provides the connection between the primary lines 48 in parallel the openings 40 ago. However, if the latter are closed as soon as the piston 13 to the left is moved, it maintains this connection until the one acting in space 16 and on piston 29 Pressure overcomes the resistance created by the counteracting spring and by the in space 31 prevailing pressure is opposed. This arrangement enables the insulation to be relocated the primary lines 48 in a later phase of the braking process and the achievement of differentiated equalization effects in the course of the development of the braking effect. The dimensioning of the spring allows the transition point to be chosen at will Consideration of an optimal mode of operation in each special case.

Of course, as in the arrangement according to FIG. 1, and to an even greater extent, since the on the piston 29 acting spring this time tends to make the chamber 31 effective, the Maintain hydraulic pressure equalization in the primary circuit in the event of a fault in the secondary circuit.

The arrangement shown in Fig. 5 is similar to that shown in Fig. 2, but only on two front wheel brakes 100 applied, while the rear brakes 101 differ in their arrangement from the usual Are kind. The secondary circuit 23 is only assigned to the front brakes 100, which are on the primary side are supplied by two lines 48. The master cylinder 10 has two bores 37 instead of four. The rear brakes 101 are supplied on the primary side via lines 102, which at 103 are supplied with the room 16 of the pump 10 are in communication.

In the arrangement according to FIG. 6, the rear brakes 101 are separated from the space 16 instead of on the primary side Supplied from the secondary side via district 23. You will be considering a minor additional Rotational movement of the front brakes 100 actuated.

In Fig. 7, an embodiment of the master cylinder is shown, which is for use in assemblies according to FIG. 5 or 6, in particular according to FIG. 5, is suitable. The master cylinder shown in FIG is similar to that shown in Fig. 1, so like reference numerals are used to denote similar elements were used. In Fig. 7, the piston 11 controlled by the pedal 12 can be seen again, as well as the Oil space 16 between the pistons 11 and 13, on the one hand at 18 with the container 19 and on the other hand at 103 with the line 102 in connection, the primary side of the rear brakes, which are of the usual Kind are supplied.

The brake cylinders of the front brakes are both by a primary circuit and by a Secondary circuit supplies. It is provided in this case that during the approach phase Brake shoes proportional oil volumes are promoted in the primary circuit and in the secondary circuit. For this purpose, the secondary circuit is not, as in the arrangement according to FIG. 1, from space 16, but how the primary circuit is supplied with liquid under the action of the movements of the piston 13.

The secondary circuit 23 is via the valve 24 not with the space 16, but with the space 41 in Link. This is at 42 with the container 43 via a valve 70, the shaft 71 of which with the piston 13 cooperates, connected. The piston 13 is assigned a spring 72 which acts on a sleeve 73, which is slidably arranged in the cylinder of the pump. The spring 72 is dimensioned so that it is not compressed when the piston 13

ίο the oil presses into the secondary circuit 23 and the valve 24 is open, but after the valve 24 has been closed by being compressed, the piston 13 can be pressed in further.
When the pedal 12 is depressed for braking, the piston 11 releases the stem 21 of the valve 20, then pushes the oil at 103 into the line 102 leading to the rear brakes, the piston 13 being pushed to the left. This in turn releases the stem 71 of the valve 70 of the space 41

zo and closes the openings 40 of the primary lines 48. The one carried by the piston 13 via the spring 72 Sleeve 73 pushes into the secondary circuit 23 amounts of oil which are proportional to those in the primary lines 48 are promoted.

The front brakes therefore experience an expansion movement which is advantageously divided between both the secondary cylinders and the primary cylinders.
When the high pressure builds up in the secondary circuit, the valve 24 closes, as a result of which a certain volume of oil is enclosed in space 41. The piston 13 is moved further with compression of the spring 72 and a differential displacement of the sleeve 73.

The construction described above in connection with the arrangement according to FIG. 5 and shown in FIG. 7 is also applicable to the arrangement of FIG. 6 in a simple manner in that the Space 16 is omitted and a connection between the pedal 12 and the piston 13 is provided. The arrangement according to FIG. 8, which is similar to that shown in FIG. 7, will now be described during the approach phase of the brake shoes proportional amounts of oil in the secondary circuit and fed into the primary circuit of the front brakes.

Instead of the spring 72 and the sleeve 73, a slide 74 enables the piston to be pushed in further 13. This slide speaks both to the pressure in space 41, which acts on its surface 75, as well as the pressure in the secondary circuit 23, which acts on its surface 76, which is in a channel 77 of the secondary circuit is located. To determine the pressure threshold above which the slide 74 yields, a counter spring 78 is provided. The return movement of the slide 74 is a Connection 79 between the space 41 and the pipe connector 42 to the container 43 is released and in this way the valve 70 short-circuited. In modification of this, the arrangement be made so that the slide 74 directly actuates the stem 71 of the valve 70.

The spring 78 is sufficiently dimensioned that the return of the during the approach phase Slide 74 is prevented and proportional amounts of oil in the secondary circuit and in the primary circuit be promoted. After the high pressure has built up in the secondary circuit, the slide 74 sets a

Connection between the space 41 and the container 43 , as a result of which the piston 13 can be pushed in further without the need for additional force to compress a spring on the pedal 12 .

In the various embodiments described above, the secondary circuit 23 is filled from the master cylinder 10 . In FIGS. 9 to 11 an arrangement is shown in which the filling takes place from the double brake cylinders 52.

Each double brake cylinder 52 has a central wall 60 which is provided with a central bore 84 between the bottom 61 of the chamber 50 and the bottom 62 of the chamber 51. A rod 86 extends through the bore 84 with considerable annular play 85. At one end of the rod 86, a plate or an enlarged head 87 is attached which extends into the chamber 51 and serves, with the base 62, a valve to build. The rod 86 also extends into a bore 88 of the piston 58 in which a seal 89 is provided. The bottom of the bore 88 is in communication with the outside air at 90 in order to prevent an adverse pneumatic effect on the rod 86. A recess 91 is provided in the base 61, via which the chamber 50 and the bore 85 are in communication even when the piston 58 is in contact with the base 61 in its rest position.

When the pedal 12 is released, the pistons 58 and 59 assume their respective rest positions under the action of the elastic return elements of the jaws 55 and 56 (FIG. 9).

In this position, the rod 86 rests against the end of the bore 88, while the head 87 is at a distance from the floor 62. The chambers 50 and 51 are in communication with one another via the channel 85, so that the secondary circuit 23 is in communication with the lines 48 and is supplied with oil from the same container.

When a force begins to be exerted on the brake pedal 12, the lines 48 of the primary circuit are put under pressure and the circuit 23 is also acted upon by this. The restoring forces acting on the pistons 58 and 59, which oppose the displacement of the pistons under the action of the pressure, are dimensioned so that the piston 59 can only be moved at a pressure that is determined by the choice of the diameter of the bores in the chambers 50 and 51 is determined in order to bring about the most suitable degree of filling in each chamber. In the example shown, the diameter of the chamber 51 is greater than that of the chamber 50, but can be the same size or also smaller.

As soon as the pressure in the chambers 50 and 51 reaches a to move the piston 58 sufficient value, shifts this together with the rod 86 to the left until it assumes the position shown in Fig. 10, in which the head 87 rests against the bottom 62 .

Beyond this position, the piston 58 continues its stroke alone (FIG. 11), the head 87 remaining in contact with the base 62 , in accordance with the difference in the cross-sections exposed to the pressure. As soon as the brake shoes touch the drum, the pressure in the chambers 50 and 51 rises further, and the higher pressure then prevailing in the chamber 51, which is added to the difference in cross-sections, holds the head 87 at the bottom 62 and with higher pressure ensures the complete closure of the chambers.
When the brake is released, the head 87 remains in contact with the floor 62 up to the position shown in FIG. 10, then lifts off under the restoring action of the piston 58 until it reaches the position shown in FIG. 9, this latter movement thereby

ίο it is made possible that any stronger pressure in the chamber 51 is canceled.

This arrangement ensures the automatic replenishment of the secondary circuit 23 through the connection to the lines 48. In particular, causes each of the secondary circuit 23 and especially at the time of the brake disengagement occurring negative pressure, the automatic opening of the valve 87 and the return flow of the liquid, which in an advantageous manner by the Return movement of the piston 58 is facilitated. Every

ao safety is guaranteed during the application of the braking force. In the event of the lines 23 breaking, the valve 87 is forced to close by the piston 59 resting on it. In the event of a break in the line 48 connected to the chamber 50, the pressure in the chamber 51 acting on the head 87 holds the piston 58 in the position shown in FIG.

The invention is applicable not only to brakes of the type shown in FIG. 3, but also to any other type of suitably designed brakes. In Figs. 12 and 13, for example, there is one Application of the invention to a disc brake shown.

In FIG. 12, 120 designates a part designed as a disk and rotating with the wheel, against which friction linings 121 can be pressed by means of a piston 123 which is mounted in the housing 122. The hydraulic pressure chamber of the piston 123 is designated by 124.

Instead of in the radial direction, as in the arrangement according to FIG. 3, the brake is applied in this case in a direction parallel to the wheel axis, a limited sector of the disk 120 being affected. The reaction force, which is produced by the pressing of the disk 120 at the point of the mentioned sector, is therefore directed tangentially and tends to displace the housing or the holder 122 in this direction. The housing 122 is fastened at its ends 125 and 126 to a fixed part 127 of the vehicle chassis, for example on the engine gearbox block 127. The fastening of the ends 125 and 126 is such that the movement play of one of these ends is smaller than that of the other end, so that the reaction force is shifted to this end. For example, the reaction force occurs as a pull at end 126 .

According to the invention, the end 126 of the housing has a cylinder 128 in which a piston 129 is slidably arranged. The piston 129 is articulated on a shaft 130 fastened to the block 127 and delimits two chambers 131 and 132 in the cylinder 128. These chambers can have different or the same diameter.

The fluid pressure in the chamber 131 is proportional to the reaction force transmitted to the housing 122 and received by the axle 130. The chamber 131 is connected to the secondary circuit 23 , which, as before, has the consequence that the

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Counterpressure forces of two or more brakes are equalized.

The other chamber 132, ie the compensation chamber, is connected according to the invention to the primary or working chamber 124 , so that the mode of operation is similar to that described in connection with the brake shown in FIG. The line of the primary circuit to the respective brake is denoted by 48. The line 48 supplies both the chamber 124 of the working piston 123 via a line 133 and the compensating chamber 132 via a line 134. Advantageously, a centering device, such as that shown in Fig type shown. 3, provided to the unit 128-129 in a specific To give rest position in which the secondary chamber 131 retains a certain oil supply.

It should be mentioned here that the device shown in FIG. 13 with a secondary or counterpressure chamber 131 and with a primary or equalization chamber 132 can be used within the scope of the invention for any type of brake which has a primary chamber as a working chamber in cooperation with a Has primary circuit with independent lines.

The arrangement shown in Fig. 14 is similar to that shown in Figs. 12 and 13 and relates to a complete alignment of two brakes, but the secondary circuit being mechanical rather than hydraulic. In FIG. 14, the two separate primary lines 48 and the compensation chambers 132 of the cylinders 128, which are arranged on the counter-pressure ends 126 of the housing 122 , can be seen. In this arrangement, the secondary chambers are. 131 and the secondary circuit are omitted and replaced by the following mechanical arrangement. The end of the cylinder 128 is formed with an extension 135 which is articulated at 136 to an elongated hole 137 of a rocker arm 138. The elongated hole 137 enables a lateral displacement in adaptation to the wear of the friction linings 121.

The rocker arm 138 is pivotably mounted in its center at 139 on the motor gearbox block 127. The lines 48 can be supplied from any master cylinder by means of which they can be made independent of one another at least during an operating phase, for example from the master cylinder 10 of the type described above, but without a hydraulic secondary circuit.

Claims (18)

PATENT CLAIMS: 1. Actuating system for vehicle brakes, in particular motor vehicle brakes, with a hydraulic primary circuit which comprises a master cylinder to be operated by means of the brake pedal and wheel brake cylinders in line with the master cylinder, and with a secondary circuit with displaceable secondary organs in each brake that absorb the supporting forces of the brake shoes , as well as coupling means which equalize the supporting forces on the secondary organs of the different brakes, characterized in that for the two brakes of the two wheels at least one axle each has a primary hydraulic linkage with a pressure chamber (37) and an intermediate piston (36) in the master cylinder it is provided that means are provided which cause the intermediate pistons to cover equal distances during braking, and further means by which a hydraulic connection between the primary hydraulic linkage can be established or disconnected. 2. Actuating system according to claim 1, characterized in that the further means have a connection between the primary hydraulic linkages when the brake pedal (12) is released. 3. Actuator according to claim 1, wherein the secondary circuit is a hydraulic circuit is, characterized in that between the secondary circuit (23) and a replenishment source (16) Connecting means (24) are provided which respond to the state of the brake pedal (12), such that they are both at rest and at the beginning of each depression of the brake pedal are effective and become ineffective if the brake pedal is depressed further. 4. Actuating system according to claim 3, characterized in that the replenishment source (16) in their pressure depends on the state of rest or the depressed state of the brake pedal (12), such that the changes in capacity and possible losses of the secondary circuit (23) on the one hand in the idle state by a permanent connection (20) of the replenishment source (16) with a container (19) under static pressure and on the other hand with each stroke of the brake pedal be balanced under the effect of the pressure generated in the circles. 5. Actuator according to claim 3, characterized in that the replenishment source by a Chamber (16) of the master cylinder (10) is formed (Fig. 1). 6. Actuator according to claim 3, characterized in that the replenishment source (50) through the primary circuit (48) is formed (Fig. 3,9,10,11). 7. Actuator according to claim 1, wherein the secondary circuit is a hydraulic circuit is, characterized in that the means (32) for establishing and disconnecting the connection between the primary hydraulic linkages by the pressure of the secondary circuit (23) in the Be influenced in such a way that they cause a change in the operation of the primary circuit, when the secondary pressure exceeds a certain value. 8. Actuating system according to claim 7, characterized in that the hydraulic linkage of the primary circuit (48) are independent above the transition value of the secondary pressure and below this value are connected to each other via (33, 34) , such that a primary compensation in the event of a fault of the secondary circuit is maintained. 9. Actuator according to claim 8, characterized in that said transition value is approximately zero, so that the primary Linkage can be made independent from the beginning of the braking process. 10. Actuator according to claim 1, wherein the secondary circuit is a hydraulic circuit is, characterized by a master cylinder (10), the first by the brake pedal (12) actuated piston (11) and a second piston (13) for displacing the liquid in the primary circuit (48), wherein the liquid space (16) is connected between these two pistons (11 and 13) with a container (19) and the secondary circuit (23) via two valves (21 and 25) each actuated by one of the two pistons. 11. Actuating system according to claim 10, characterized in that individual pistons (36) are provided to displace the liquid in the hydraulic linkage of the primary circuit, which are actuated by the second piston (13) of the main cylinder (10), the pressure chambers ( 37), in which these pistons (36) work, with a container (43) via channels (40) which are closed when the second piston (13) is pressed in at a certain depth, and with one another via a channel (33, 34) which is closed at a certain pressure in the liquid space (16) between the two pistons (11 and 13) , are in connection (Fig. 1). 12. Actuating system according to claim 1, in which the secondary circuit is a hydraulic circuit, characterized by a master cylinder (10), in which individual pistons (36) are provided for displacing the liquid in the hydraulic linkage of the primary circuit (48), which are provided by an aggregate are actuated, which is shifted depending on the movements of the brake pedal (12), the pressure chambers of these pistons being in communication with a chamber (41) via channels (40) which are closed at a certain depth of depression of the unit, and the chamber (41) is connected to a container (43) and to the secondary circuit (23) via two valves (70 and 24) , which are actuated by the unit, in such a way that during the approach phase of the friction surfaces of the brakes, proportional amounts of fluid enter the primary circuit (48 ) and in the secondary circuit (23) are promoted, while means are provided which allow the further pressing of the unit after this phase (Fig. 7 and 8th). 13. Actuating system according to claim 12, characterized by a spring (72) which between one piston (13) of the unit and one between the cylinder (10) and this piston (13) displaceably arranged sleeve (73) is arranged compressible (Fig. 7). 14. Actuating system according to claim 12, characterized by a slide (74) which is on the pressure in the space (41) and / or in the secondary circuit (23) responds and a connection (79) this space (41) with the container (43) canceling the effect of this associated Valve (70) opens (Fig. 8). 15. Actuator according to claim 1, wherein a brake one drum and two Has jaws, each of which is supported against cylinder piston, one of which is to the primary circuit and the other belongs to the secondary circuit, characterized by a rod (64) which arranged between two abutments (58 α and 59 a) connected to the two pistons (58 and 59) and with a resilient (67) abutment (65) for fixing a liquid supply in the Secondary cylinder (51) is provided, and by a spring (63) for returning the jaws (55 and 56) in their release position. 16. Actuating system according to claim 1, characterized in that the cylinders (124) of the wheel brakes are connected to the master cylinder via lines (133) of the primary circuit (48) and are arranged in housings (122) which, in the operative position, the rotating part (120 ) of the brake and are mounted displaceably with respect to a block (127) so that the braking reaction transmitted to the housing (122) is absorbed by an element (129) connected to the block (127) via the axis (130) and the latter is displaceable with respect to the housing and with this forms a chamber (132) which is in communication with the primary circuit (48) via a line (134), while clutch means (131, 138) which equalize the braking reactions of the various brakes , act between the housings (122) (Figs. 12 and 14). 17. Actuating system according to claim 16, characterized in that the secondary circuit is a hydraulic circuit (23) which is in communication with a chamber (131) which is delimited in the housing (122) by the piston (129) and the chamber ( 132) , which in turn is connected to the primary circuit (48) via a line (134) (FIG. 12). 18. Actuating system according to claim 16, characterized in that the secondary circuit is mechanical and consists of a vibrating element (138) which is coupled to the housings (122) of the brakes (Fig. 14). Considered publications: German Patent No. 704 693; French Patent Nos. 768,371, 972,668; U.S. Patent Nos. 1 630 178, 2115 995,
041, 2,369,313, 2385,812; LA VIE AUTOMOBILE from October 15, 1954, pp. 259 to 263. In addition 4 sheets of drawings © 109 618/297 6.